Process for producing a heald shaft for weaving shafts out of a metal hollow section

ABSTRACT

The invention concerns a process for producing a heald shaft for weaving shafts out of a metal hollow section, the height of which diminishes towards the ends on both sides. A light-weight extruded metal section is selected and adjusted to the maximal height of the section of a heald shaft without center support, whereupon the heald shaft is reduced towards both of its ends.

FIELD OF THE INVENTION

The invention concerns a process for manufacturing a heald shaft forweaving shafts in correspondence with the generic term of the mainclaim.

BACKGROUND OF THE INVENTION

Light-weight and rigid weaving shafts are necessary for high-performancelooms with up to 2000 fills/min. Acceleration values which permit thehighest weft efficiency with an economical justifiable energyconsumption are attainable only with light-weight weaving shaft healdsystems. For a trouble-free weaving process, heald shafts must be asrigid as possible.

In the past, weaving shaft design has been adapted to the progressingincrease in loom efficiency essentially by increasing the height of theheald shaft cross section for decreasing the severity of sagging. Sinceextruded sections are usually employed for the heald shafts, thisapproach is subject to limitations because of the associatedconsiderable increase in the weight of the sections. A further increasein weaving shaft weight necessitates more powerful drive units for theweaving shafts and a considerably higher energy consumption, and thusrenders further increases in weft efficiency uneconomical.

In DE 39 37 657 A 1, it is shown that weaving shafts with heald shaftsconsisting of carbon fiber or carbon fiber hybrid materials arecurrently employed for solving this problem. Decided advantages arelight weight and high flexural strength because of the high elasticmodulus, in comparison with an extruded aluminum section of equalheight. Serious disadvantages of this proposal are the high price, whichis several times that of a comparable aluminum section, as well as theunsolved problem of disposal of worn-out weaving shafts.

In the following references, that is, EP 496 054 A 1, DE 36 21 145 A 1,and DE 37 02 524 C 2, a different solution is proposed for the problem;that is, the upper and lower heald shafts of the proposed weaving shaftsconsist of a combination of steel sections, thin steel sheets, andlight-weight frame structures. Weaving shafts produced from thesesections are somewhat lighter than comparable aluminum weaving shafts,but the flexural strength is somewhat lower, and the price is abouttwice as high.

Finally, in U.S. Pat. No. 3,754,577, the addition of planking with railsor sheets of steel or carbon fibers in partial zones of extrudedsections is proposed for increasing the flexural strength.

All of these proposed and in part practiced problem solutions ignore thestate of the art, which implies that a beam on two supports shouldlogically exhibit the highest geometrical moment of inertia in the zoneof highest stresses.

In Austrian Patent 25 82 24, the insertion of a single hollow section ofsteel or aluminum as basis heald shaft with relatively low overallheight is proposed for this purpose. By means of webs fastened to theback of the heald shaft, for instance, with screws or rivets, or bywelding, whose height increases from the ends of the section toward themiddle, higher flexural strength is envisaged and achieved with theleast possible increase in weight. The web height in the middle can varyin correspondence with the length of the weaving shaft, or incorrespondence with the load. However, this inherently ideal weavingshaft design also has not proved its worth in practice because of thecost, since the manufacturing process is evidently too expensive, andadaptation to match the wide variety of possible applications presentsdifficulties.

Another solution provides for one or more so-called central supports,which are frequently inserted between the upper and lower shaft sectionsfor weaving shaft lengths as of 250 cm nominal width, if greater shaftweight is not tolerable. These central supports are an extremelyunpleasant means of reducing the sag of the section, since they hindermanipulation in healding and frequently result in weaving defects andtrack during the weaving process.

The purpose of the present invention is to produce a weaving shaft whichdoes not require a central support, even for large machine widths; atthe same time, the weight of the weaving shaft must remain within thelimits specified by loom and shaft machine manufacturers; finally, aneconomical manufacturing process which permits the use of recyclablematerials is proposed.

SUMMARY OF THE INVENTION

The invention involves a process for manufacturing a heald shaft forweaving shafts. The heald shaft made according to the invention is madefrom an hollow metal section that has been tapered at both lateral ends.The process includes steps of extruding a light metal section with adesired section height and subsequently tapering both ends of theextruded light metal section.

BRIEF DESCRIPTION OF THE FIGURES

The FIGURE illustrates a portion of a heald shaft made in accordancewith the process of the invention.

DETAILED DESCRIPTION

The FIGURE illustrates the heald shaft made according to the invention.Seen in the FIGURE is a portion 1 of a heald shaft. The maximum sectionheight is noted at 2, while an open chamber made by tapering the shaftis seen at 3.

In other words, the use of an extruded light metal section as healdshaft is proposed; its height thereby corresponds to the necessarymaximal section height of the heald shaft. That is, the basis sectionmust be as high as necessary for assuring acceptable sag of the healdshaft in the middle. The section height thus determined for a weavingshaft without central support is considerably greater than for thesections usually employed at present for heald shafts with centralsupport. Furthermore, it is proposed that this relatively high healdshaft be tapered from the middle toward both ends, in order to decreasethe weight without impairing the dynamic performance of the heald shaft.

A single-component extruded section, preferentially of aluminum, whichrequires no further machining other than tapering toward the ends, isproposed.

Since the shaft sections in part have open section chambers as a resultof tapering for the purpose of weight reduction, these open chambers areclosed with light materials on the upper heald shaft, if necessary; thismeasure ensures that no accumulations of fiber flocks can form in theopen back of the section during cotton weaving, for instance, and fallinto the woven materials at any time, thus causing malfunctions orweaving defects.

The additional, preferentially cutting machining for decreasing thesection weight can be performed economically in a chucking operation inthe course of the other machining processes at a programmable centralmachining facility.

The additional material consumption for the higher extruded sectioncauses only a fraction of the costs which would otherwise result fromthe use of complicated section structures of hybrid design, of carbonfibers, or elaborate reinforcement measures.

What is claimed is:
 1. Process for manufacturing a heald shaft for weaving shafts from a hollow metal section, whose height decreases toward both ends, the process comprising steps of:extruding a light metal section having a section height selected to match the maximal section height of a heald shaft without central support; and tapering both lateral ends of the light metal section.
 2. Process as claimed in claim 1, wherein the step of tapering both lateral ends of the light metal section comprises a machining step.
 3. Process as claimed in claim 2, wherein the machining step comprises a step of producing open section chambers.
 4. Process as claimed in claim 3, further comprising a step of closing the open section chambers produced in the upper heald shaft by machining.
 5. Process as claimed in claim 4, wherein the closing step comprises using lightweight materials.
 6. A heald shaft for weaving shafts, the heald shaft comprising an extruded hollow light metal shaft having a section height selected to match the maximal height of a heald shaft without central support; wherein the light metal shaft tapers at each lateral end.
 7. The heald shaft as claimed in claim 6, further comprising open section chambers produced by machining the extruded light metal shaft.
 8. The heald shaft as claimed in claim 7, wherein the open section chambers are closed with lightweight materials. 